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4.3 PROTEINS

4.3 PROTEINS. Elements in protein. Carbon, hydrogen, oxygen, nitrogen, sulphur & phosphorus Basic unit: amino acids Amino acids are joined to each other in a particular sequence to form polypeptide chain or protein. Formation and breakdown of dipeptides & polypeptides. Peptide bond.

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4.3 PROTEINS

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  1. 4.3 PROTEINS

  2. Elements in protein • Carbon, hydrogen, oxygen, nitrogen, sulphur& phosphorus • Basic unit: amino acids • Amino acids are joined to each other in a particular sequence to form polypeptide chain or protein Tr.Rez@SB2013

  3. Formation and breakdown of dipeptides & polypeptides Peptide bond condensation + H2O + hydrolysis Amino acid Amino acid dipeptide Tr.Rez@SB2013

  4. condensation + + + 2H2O hydrolysis Amino acid Amino acid Amino acid tripeptide Tr.Rez@SB2013

  5. condensation A polypeptide chain hydrolysis + 9H2O * 10 to 100 amino acids Tr.Rez@SB2013

  6. Protein Structures • Complete protein molecule is a simple unbranched chain of amino acids • 3D protein structure is classified into 4 levels: • Primary structure • Secondary structure • Tertiary structure • Quaternary structure Tr.Rez@SB2013

  7. keratin silk Tr.Rez@SB2013 Enzymes, hormones, antibodies, haemoglobin

  8. Essential amino acids & Non essential amino acids • Essential: • Amino acid that required for protein synthesis, but cannot be synthesized in the human body • Obtained from food we eat • Non essential: • Amino acid that is required for protein synthesis and can be synthesized by humans Tr.Rez@SB2013

  9. Protein from food divided into: • 1st class protein (complete protein) • Contain all the essential amino acids • Are animals proteins like meat, fish, dairy and eggs • Second class proteins (incomplete protein) • Are low in one or more of the essential amino acids • Plant proteins like vegetables, beans, peas grains, nuts & seeds Tr.Rez@SB2013

  10. LIPIDS

  11. LIPIDS • Consist of C,H and O • High hydrogen to oxygen ratio • Non polar hydrophobic compounds • Include FATS, OILS, WAXES, PHOSPHOLIPIDS and STEROIDS • Fats and oils similar chemically • At room temperature, fats are solid and oils are liquid Tr.Rez@SB2013

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  14. Components of fats & oils • 2 different kinds of organic molecules that join to make fats & oils are: • Glycerol • Fatty acid Tr.Rez@SB2013

  15. Glycerol • Colorless, odorless, sweet –tasting syrupy liquid • 3 carbon and 3 hydroxyl group (OH) Tr.Rez@SB2013

  16. Fatty acid • Organic acid • Molecular structure • Long hydrocarbon tail with carboxyl (-COOH) at one end • Different fatty acids have different hydrocarbon tails Tr.Rez@SB2013

  17. Formation & breakdown of fats & oils Tr.Rez@SB2013

  18. Saturated fats vs unsaturated fats Solid state at room temperature Are in the liquid state (oil) at room temperature Tr.Rez@SB2013

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